Currently, there exists numerous converters which utilize power transistors. One application of power transistors is in conventional power supplies. In a power supply, the power transistors are used to switch high voltages. Such converters which utilize power transistors may be subjected to fault currents. A fault current through the power transistor causes serious damage to the power transistor as well as other components of the converter. These fault currents may be a product of short circuits or current shoot-through.
The prior art has responded to the above-referenced problems by offering complex protection circuits having multiple circuit devices. Such circuits include delay protection circuits for current shoot-through, and protection circuits for short circuits. The addition of the referenced protection circuits are not only in many instances slow to react to a detected fault current but are also costly to implement. One common scheme, desat protection, must be disabled during and shortly after switching times. Another common scheme, phase current protection, does not measure device current and thus cannot protect against shoot-through.
As such, a need exists for a new and improved protection circuit for a power transistor. The new and improved protection circuit must be capable of reacting quickly to a fault current, and must contain minimal additional components such that the protection circuit is low in cost without compromising reliability.